ChIP-seq: embryos, L2/L3s and adult worms were dounce-homogenized in FA buffer (50 mM HEPES/KOH pH 7.5, 1 mM EDTA, 1% Triton X-100, 0.1% sodium deoxycholate; 150 mM NaCl) and sonicated in 0.1% sarkosyl to obtain chromatin fragments between 200 and 800 bp. 2 mg of protein extract and 3 to 10 ug of antibody was used per ChIP. ChIP-seq: half of the ChIP DNA and 30 ng of input DNA were ligated to Illumina TruSeq adapters and amplified by PCR. Library DNA between 250 and 600 bp was gel purified.